Fuel System Flashcards
What are fuel suction valves?
In the inner tank.
Valves normally held closed by tank fuel pressure created by tank pumps.
When there is an electrical failure, the valves open when pressure drops to allow gravity feeding
What is the tank vent surge function?
Vent tank surge is a fuel system protection that prevents fuel tank failure due to heat expansion of the fuel.
Fuel vent surge valve is located on outside of outer tank and will spill excess fuel overboard
Fuel can expand by 2% or increase in temp of 20*C
What side supplies the APU?
Supplied by fuel from engine 1 side
How is fuel pressure supplied to APU when system not pressurised?
Special APU fuel pump powered by batteries
Describe fuel recirculating system
Fuel from HP fuel line is diverted through the heat exchanger of the IDG. Heat from the oil is radiated away by the fuel in the exchanger.
It is then sent either to the HP fuel line or sent back to the outer tanks
How is Centre Tank fuel prioritised in the traditional A320 system
CT fuel pumps deliver fuel at higher pressure than inner tanks. As a result the CT pumps drain fuel before the inner tanks
What is the fuel feed sequence of a traditional A320?
Centre tanks for 2 mins or until slats extended
Inner tanks until 500kg used
CT until empty (may turn off if recirc fuel puts it up above 500kg limit)
Inner tanks to 750kg
Outer tanks to inner tanks
Why is CT fuel prohibited for TO?
Wing tanks fill before CTs. If fed from CT during TO then recirculated fuel would go into full wing tanks and cause the surge vent to spill excess overboard
How is fuel system different on modern A320? Fuel feed sequence?
Only inner tanks provide fuel to engine. CT fuel drains into inner tanks via transfer valves and jet pumps.
Fuel is burned from inner tanks until 250kg used. Centre tank transfer valves open and jet pumps activate. If the inner tanks fuel then reaches the high level sensor the jet pump switches off and the valves close. The process is repeated until CT is empty. Then as per traditional A320
Can you refuel on batteries only?
Yes, switch on refuel panel enables it
What are jet pumps? How many?
1 jet pump in each inner tank
Creates a vacuum that sucks fuel through transfer valve from CT to inner
What is CT fuel inerting system?
When fuel is burned from CT, it is replaced by air from bleed system which has been starved of oxygen so less explosive
Trip fuel modifications?
Increase by 5kg per nm
Decrease by 4kg per nm
Fuel system procedures (defuelling/gravity fuelling/refuelling with engine running) found where?
FCOM/PRO/SUP/FUEL
Which QRH procedures are related to fuel?
Fuel imbalance
Fuel leak
Gravity fuel feeding
